X-ray Microscopy

Micro-CT uses an X-ray source to visualise the surface and internal structures of a specimen in three dimensions, without extensive or destructive specimen preparation. The maximum resolution attainable with Micro-CT depends on the size of the sample being scanned as well as the equipment. Generally, each additional millimetre of sample diameter increases pixel dimensions by one micron e.g. a 15mm diameter bone will comfortably scan at 15 micron pixel resolution.

During scanning, the specimen is rotated in small increments over 180°C or 360°C and an X-ray projection image is captured at each step. After scanning, a cone-beam reconstruction program is used to turn the projection images into a stack of hundreds or even thousands of cross-sections which can be used with a variety of image analysis and 3-D volume rendering software packages for 2-D or 3-D morphometrical analysis, or to produce 3-D images and animations.

Micro-CT relies on a density difference between the structure of interest and the surrouonding material. Porous materials (minerals, ceramics, polymers) are particularly well suited to this method. Other applications include bone, teeth, lung tissue, archaeological and paleontological specimens, coral and wood.

Xradia MicroXCT-400

X-ray energy range:40 kV - 150 kV.

The maximum sample size that can be imaged in this system is 40 mm diameter. Taller samples can be scanned (up to 200 mm) and then stitched together in post processing. The MicroXCT-400 is capable of submicron resolution (0.7 µm) for samples smaller than 1 mm in diameter. It collects images in absorption contrast mode making it suitable to image a wide range of specimens including both hard and soft biological tissues as well as minerals, ceramics, polymers etc.

Xradia NanoXCT-100

X-ray energy fixed at 8 kV.

The NanoXCT is a specialised instrument that can scan small samples with a resolution down to 50 nm. It can non-destructively obtain 3-D information from internal structures at 2 volumes: 64 µm3 (resolution 150 nm) and 16 µm3 (resolution 50 nm). Sample diameters need to be 100 µm or less to achieve the highest resolution. It can image in absorption mode as well as phase contrast (improving image contrast for low-atomic-number samples and the ability to scan soft biological specimens and polymers). Instrument scan times are quite long with a single scan taking two to five days for optimal results.

Skyscan 1172

X-ray energy range: 20 kV - 100 kV.

The maximum resolution attainable with this system is approximately 2 µm. At lower resolutions (24 µm) sample sizes may be as big as 5 cm3, while at higher resolutions the maximum sample size may be 4-5 mm3.

A Materials Testing Stage is also available for this system allowing for in-situ tensile and compressions tests.